1921 Router Config Help

[cwasilak]

Hello, I know very little about configuring cisco hardware and need some help..... we are currently running an 1800 router and I obtained a new to me 1921 router and would like to replace the 1800 router with the newer one, I managed to get it factory reset but need help getting the config from the 1800 to the 1921 I have the config file and tried copying it but the 1921 is different. Can someone convert my config file for me?

Thanks 

[cwasilak]

Sorry, I leave at 5

Thanks

[liviu.gheorghe]

Ok, it's starting to make sense. Can you also send me the output of the show running-config from the other 3560 switch?

[cwasilak]

LG,

I was able to do some more testing this afternoon, when I plug the 1921 into the network, everything internally seems to still work fine, but I have no internet, also from my desktop i had a constant ping going to 10.255.255.254 with the 1800 plugged in I get responses with the 1921 plugged in I got request timed out, also from the 1921 plugged in I was able to successfully ping the internet 8.8.8.8 and 208.67.222.222 I could also ping internally 10.0.0.2

[liviu.gheorghe]

When you ping the 1800 router from your desktop, it determines the MAC address associated with 10.255.255.254, uses it to send the ethernet frames to the router and stores it in the ARP cache.

When you change the 1800 with the 1921, the 1921 has the same IP address as the 1800, but it's MAC address is different. Your desktop still has in it's ARP cache:

10.255.255.254   MAC address of 1800 router

so your desktop will send ethernet frames to a non-existing MAC address and no host on the LAN will answer those ICMP echo packets.

In order for this to work, you should clear the ARP cache on the desktop after changing routers - open a Power Shell, run as administrator, and issue the command arp -d *

Now your desktop will re-discover the MAC address associated with the 1921 router and ping should be successful.

[cwasilak]

LG, I was able to get the router working, I needed to reboot the switch it was plugged into, thank you for all of the assistance, would you be able to help me the same way going from an asa5510 to asa5525-x I started to try moving all of the settings over but then it got a little confusing.

Thanks

[liviu.gheorghe]

You are welcome. Happy to help.